Professor John Doyle:

The authors have allowed for the full gross cost. If on day one of a united Ireland, every public servant in the North were immediately, without any negotiation on terms and conditions or trade union negotiations, put on the much higher wages in the South, which have been prevalent across the private and public sectors – it is not exclusively a public sector issue – the gross cost would be €4.2 billion. However, there is no circumstance in which that would be paid tax-free. It is not marginal; it would be 54% of the cost if we assumed it were happening today, with the current tax rates, PRSI rates and pension arrangements. You have got to assume that if this happened in ten years' time, there would not be a radical difference. It is more than half the cost. It is simply not a factor for discussion and it would never arise, even if you decided to have the increase on day one of a united Ireland, which I would argue is an unlikely outcome for all sorts of reasons, not least that the cost of living would not increase the following morning. The cost of living would converge over time, not instantly. Housing is the biggest driver, and housing costs. They change, but they do so over time, not instantly.